Do you save more energy by turning off the AC for a while or leaving it on?

Question

Which way do you save more energy, by leaving the AC on all day and putting it in a higher temperature while nobody is at home or by turning it off while nobody is at home?

My roommate and I are usually not at home from 8am to 5pm every day. We live in a 2 bedroom apartment in the second floor (out of 3 floors) in Texas. I usually turn the AC off while we are both out, but he told me yesterday that we might save more energy if we leave the AC on and just put it in a higher temperature while we are gone since it takes so much energy to cool down the entire place. It usually gets around 100 degrees outside during the day, but we live in the second floor out of three floors so it shouldnt get that hot inside.

Is my roommate right?

betotron don · Accepted Answer

off is the key! when you get home turn on the fan to circulate the hot air out! open a couple windows. 20 minutes later turn on ac and close up the windows>invest in humidifyer as texas is full of hot wet air! very uncomfortible! you will notice the difference right away!

Anonymous · Answer

weelll....how long does it take to chill down the room? if thats less than 9 hours then you are saving energy turning it off....

i drive fridge trucks sometimes and have heard this sort of nonsense from other drivers. i never yet had a trailer that didn't chill down to -18 in more than an hour, what's the point of driving a load of chilled air about?


of course, the best thing would to leave a skylight open and then open all the doors and windows when you get home, eat on the terrace and never turn the gas-guzzling air conditioning on at all. or move somewhere cooler.

gadfly · Answer

It will come out the same. If you leave it off during the day, its going to take the same amount of energy to cool down the hot apartment than if you left it on all day. It doesn't even make sense to put it at a higher setting than you have when you are at home. This is why they have thermostats. You gain nothing but coming home to a hot appartment/house by changing the settings.

Anonymous · Answer

The more you turn it up, the more money you will save.  It will take less energy to bring the temp back down than it would have taken to keep it down.

You can buy programmable thermostats for 50 bucks or so that can have it cool when you walk in from work.  As regular as your schedule seems to be, one of these would work well.

big nickel · Answer

regardless were the apt is it will get hot your better off turning it up a bit so when you get home it does not have to suck so much energy to cool the place down and at a higher temp you will get used to that and not need to cool it down so much

Anonymous · Answer

Good Question, i was just about to write the same one...

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Do you save more energy by turning off the AC for a while or leaving it on?

6 Answers